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<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2011 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: AbstractSchemaUpdater.html 740 2013-10-02 21:27:31Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.dellroad.stuff.schema;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>import java.util.ArrayList;<a name="line.10"></a>
<span class="sourceLineNo">011</span>import java.util.Collection;<a name="line.11"></a>
<span class="sourceLineNo">012</span>import java.util.Collections;<a name="line.12"></a>
<span class="sourceLineNo">013</span>import java.util.Comparator;<a name="line.13"></a>
<span class="sourceLineNo">014</span>import java.util.HashSet;<a name="line.14"></a>
<span class="sourceLineNo">015</span>import java.util.Iterator;<a name="line.15"></a>
<span class="sourceLineNo">016</span>import java.util.LinkedHashSet;<a name="line.16"></a>
<span class="sourceLineNo">017</span>import java.util.List;<a name="line.17"></a>
<span class="sourceLineNo">018</span>import java.util.Set;<a name="line.18"></a>
<span class="sourceLineNo">019</span>import java.util.TreeMap;<a name="line.19"></a>
<span class="sourceLineNo">020</span>import java.util.TreeSet;<a name="line.20"></a>
<span class="sourceLineNo">021</span><a name="line.21"></a>
<span class="sourceLineNo">022</span>import org.dellroad.stuff.graph.TopologicalSorter;<a name="line.22"></a>
<span class="sourceLineNo">023</span>import org.slf4j.Logger;<a name="line.23"></a>
<span class="sourceLineNo">024</span>import org.slf4j.LoggerFactory;<a name="line.24"></a>
<span class="sourceLineNo">025</span><a name="line.25"></a>
<span class="sourceLineNo">026</span>/**<a name="line.26"></a>
<span class="sourceLineNo">027</span> * Handles the initialization and schema maintenance of a database.<a name="line.27"></a>
<span class="sourceLineNo">028</span> *<a name="line.28"></a>
<span class="sourceLineNo">029</span> * &lt;p&gt;<a name="line.29"></a>
<span class="sourceLineNo">030</span> * In this class, a &lt;b&gt;database&lt;/b&gt; is some stateful object whose structure and/or content may need to change over time.<a name="line.30"></a>
<span class="sourceLineNo">031</span> * &lt;b&gt;Updates&lt;/b&gt; are uniquely named objects capable of making such changes. Databases are also capable of storing the<a name="line.31"></a>
<span class="sourceLineNo">032</span> * names of the already-applied updates.<a name="line.32"></a>
<span class="sourceLineNo">033</span> *<a name="line.33"></a>
<span class="sourceLineNo">034</span> * &lt;p&gt;<a name="line.34"></a>
<span class="sourceLineNo">035</span> * Given a database and a set of current updates, this class will ensure that a database is initialized if necessary<a name="line.35"></a>
<span class="sourceLineNo">036</span> * and up-to-date with respect to the updates.<a name="line.36"></a>
<span class="sourceLineNo">037</span> *<a name="line.37"></a>
<span class="sourceLineNo">038</span> * &lt;p&gt;<a name="line.38"></a>
<span class="sourceLineNo">039</span> * The primary method is {@link #initializeAndUpdateDatabase initializeAndUpdateDatabase()}, which will:<a name="line.39"></a>
<span class="sourceLineNo">040</span> * &lt;ul&gt;<a name="line.40"></a>
<span class="sourceLineNo">041</span> * &lt;li&gt;Initialize an {@linkplain #databaseNeedsInitialization empty} database (if necessary);&lt;/li&gt;<a name="line.41"></a>
<span class="sourceLineNo">042</span> * &lt;li&gt;Apply any outstanding {@link SchemaUpdate}s as needed, ordered properly according to<a name="line.42"></a>
<span class="sourceLineNo">043</span> *      their {@linkplain SchemaUpdate#getRequiredPredecessors predecessor constraints}; and&lt;/li&gt;<a name="line.43"></a>
<span class="sourceLineNo">044</span> * &lt;li&gt;Keep track of which {@link SchemaUpdate}s have already been applied across restarts.&lt;/li&gt;<a name="line.44"></a>
<span class="sourceLineNo">045</span> * &lt;/ul&gt;<a name="line.45"></a>
<span class="sourceLineNo">046</span> * &lt;/p&gt;<a name="line.46"></a>
<span class="sourceLineNo">047</span> *<a name="line.47"></a>
<span class="sourceLineNo">048</span> * @param &lt;D&gt; database type<a name="line.48"></a>
<span class="sourceLineNo">049</span> * @param &lt;T&gt; database transaction type<a name="line.49"></a>
<span class="sourceLineNo">050</span> */<a name="line.50"></a>
<span class="sourceLineNo">051</span>public abstract class AbstractSchemaUpdater&lt;D, T&gt; {<a name="line.51"></a>
<span class="sourceLineNo">052</span><a name="line.52"></a>
<span class="sourceLineNo">053</span>    protected final Logger log = LoggerFactory.getLogger(this.getClass());<a name="line.53"></a>
<span class="sourceLineNo">054</span><a name="line.54"></a>
<span class="sourceLineNo">055</span>    private Collection&lt;? extends SchemaUpdate&lt;T&gt;&gt; updates;<a name="line.55"></a>
<span class="sourceLineNo">056</span>    private boolean ignoreUnrecognizedUpdates;<a name="line.56"></a>
<span class="sourceLineNo">057</span><a name="line.57"></a>
<span class="sourceLineNo">058</span>    /**<a name="line.58"></a>
<span class="sourceLineNo">059</span>     * Get the configured updates. This property is required.<a name="line.59"></a>
<span class="sourceLineNo">060</span>     *<a name="line.60"></a>
<span class="sourceLineNo">061</span>     * @return configured updates<a name="line.61"></a>
<span class="sourceLineNo">062</span>     * @see #setUpdates setUpdates()<a name="line.62"></a>
<span class="sourceLineNo">063</span>     */<a name="line.63"></a>
<span class="sourceLineNo">064</span>    public Collection&lt;? extends SchemaUpdate&lt;T&gt;&gt; getUpdates() {<a name="line.64"></a>
<span class="sourceLineNo">065</span>        return this.updates;<a name="line.65"></a>
<span class="sourceLineNo">066</span>    }<a name="line.66"></a>
<span class="sourceLineNo">067</span><a name="line.67"></a>
<span class="sourceLineNo">068</span>    /**<a name="line.68"></a>
<span class="sourceLineNo">069</span>     * Configure the updates.<a name="line.69"></a>
<span class="sourceLineNo">070</span>     * This should be the set of all updates that may need to be applied to the database.<a name="line.70"></a>
<span class="sourceLineNo">071</span>     *<a name="line.71"></a>
<span class="sourceLineNo">072</span>     * &lt;p&gt;<a name="line.72"></a>
<span class="sourceLineNo">073</span>     * For any given application, ideally this set should be "write only" in the sense that once an update is added to the set<a name="line.73"></a>
<span class="sourceLineNo">074</span>     * and applied to one or more actual databases, the update and its name should thereafter never change. Otherwise,<a name="line.74"></a>
<span class="sourceLineNo">075</span>     * it would be possible for different databases to have inconsistent schemas even though the same updates were recorded.<a name="line.75"></a>
<span class="sourceLineNo">076</span>     *<a name="line.76"></a>
<span class="sourceLineNo">077</span>     * &lt;p&gt;<a name="line.77"></a>
<span class="sourceLineNo">078</span>     * Furthermore, if not configured to {@linkplain #setIgnoreUnrecognizedUpdates ignore unrecognized updates already applied}<a name="line.78"></a>
<span class="sourceLineNo">079</span>     * (the default behavior), then updates must never be removed from this set as the application evolves;<a name="line.79"></a>
<span class="sourceLineNo">080</span>     * see {@link #setIgnoreUnrecognizedUpdates} for more information on the rationale.<a name="line.80"></a>
<span class="sourceLineNo">081</span>     *<a name="line.81"></a>
<span class="sourceLineNo">082</span>     * @param updates all updates; each update must have a unique {@link SchemaUpdate#getName name}.<a name="line.82"></a>
<span class="sourceLineNo">083</span>     * @see #getUpdates<a name="line.83"></a>
<span class="sourceLineNo">084</span>     * @see #setIgnoreUnrecognizedUpdates<a name="line.84"></a>
<span class="sourceLineNo">085</span>     */<a name="line.85"></a>
<span class="sourceLineNo">086</span>    public void setUpdates(Collection&lt;? extends SchemaUpdate&lt;T&gt;&gt; updates) {<a name="line.86"></a>
<span class="sourceLineNo">087</span>        this.updates = updates;<a name="line.87"></a>
<span class="sourceLineNo">088</span>    }<a name="line.88"></a>
<span class="sourceLineNo">089</span><a name="line.89"></a>
<span class="sourceLineNo">090</span>    /**<a name="line.90"></a>
<span class="sourceLineNo">091</span>     * Determine whether unrecognized updates are ignored or cause an exception.<a name="line.91"></a>
<span class="sourceLineNo">092</span>     *<a name="line.92"></a>
<span class="sourceLineNo">093</span>     * @return true if unrecognized updates should be ignored, false if they should cause an exception to be thrown<a name="line.93"></a>
<span class="sourceLineNo">094</span>     * @see #setIgnoreUnrecognizedUpdates setIgnoreUnrecognizedUpdates()<a name="line.94"></a>
<span class="sourceLineNo">095</span>     */<a name="line.95"></a>
<span class="sourceLineNo">096</span>    public boolean isIgnoreUnrecognizedUpdates() {<a name="line.96"></a>
<span class="sourceLineNo">097</span>        return this.ignoreUnrecognizedUpdates;<a name="line.97"></a>
<span class="sourceLineNo">098</span>    }<a name="line.98"></a>
<span class="sourceLineNo">099</span><a name="line.99"></a>
<span class="sourceLineNo">100</span>    /**<a name="line.100"></a>
<span class="sourceLineNo">101</span>     * Configure behavior when an unknown update is registered as having already been applied in the database.<a name="line.101"></a>
<span class="sourceLineNo">102</span>     *<a name="line.102"></a>
<span class="sourceLineNo">103</span>     * &lt;p&gt;<a name="line.103"></a>
<span class="sourceLineNo">104</span>     * The default behavior is &lt;code&gt;false&lt;/code&gt;, which results in an exception being thrown. This protects against<a name="line.104"></a>
<span class="sourceLineNo">105</span>     * accidental downgrades (i.e., running older code against a database with a newer schema), which are not supported.<a name="line.105"></a>
<span class="sourceLineNo">106</span>     * However, this also requires that all updates that might ever possibly have been applied to the database be<a name="line.106"></a>
<span class="sourceLineNo">107</span>     * present in the set of configured updates.<a name="line.107"></a>
<span class="sourceLineNo">108</span>     *<a name="line.108"></a>
<span class="sourceLineNo">109</span>     * &lt;p&gt;<a name="line.109"></a>
<span class="sourceLineNo">110</span>     * Setting this to &lt;code&gt;true&lt;/code&gt; will result in unrecognized updates simply being ignored.<a name="line.110"></a>
<span class="sourceLineNo">111</span>     * This setting loses the downgrade protection but allows obsolete schema updates to be dropped over time.<a name="line.111"></a>
<span class="sourceLineNo">112</span>     *<a name="line.112"></a>
<span class="sourceLineNo">113</span>     * @param ignoreUnrecognizedUpdates whether to ignore unrecognized updates<a name="line.113"></a>
<span class="sourceLineNo">114</span>     * @see #isIgnoreUnrecognizedUpdates<a name="line.114"></a>
<span class="sourceLineNo">115</span>     */<a name="line.115"></a>
<span class="sourceLineNo">116</span>    public void setIgnoreUnrecognizedUpdates(boolean ignoreUnrecognizedUpdates) {<a name="line.116"></a>
<span class="sourceLineNo">117</span>        this.ignoreUnrecognizedUpdates = ignoreUnrecognizedUpdates;<a name="line.117"></a>
<span class="sourceLineNo">118</span>    }<a name="line.118"></a>
<span class="sourceLineNo">119</span><a name="line.119"></a>
<span class="sourceLineNo">120</span>    /**<a name="line.120"></a>
<span class="sourceLineNo">121</span>     * Perform database schema initialization and updates.<a name="line.121"></a>
<span class="sourceLineNo">122</span>     *<a name="line.122"></a>
<span class="sourceLineNo">123</span>     * &lt;p&gt;<a name="line.123"></a>
<span class="sourceLineNo">124</span>     * This method applies the following logic: if the {@linkplain #databaseNeedsInitialization database needs initialization},<a name="line.124"></a>
<span class="sourceLineNo">125</span>     * then {@linkplain #initializeDatabase initialize the database} and {@linkplain #recordUpdateApplied record} each update<a name="line.125"></a>
<span class="sourceLineNo">126</span>     * as having been applied; otherwise, {@linkplain #apply apply} any {@linkplain #getAppliedUpdateNames unapplied updates}<a name="line.126"></a>
<span class="sourceLineNo">127</span>     * as needed.<a name="line.127"></a>
<span class="sourceLineNo">128</span>     *<a name="line.128"></a>
<span class="sourceLineNo">129</span>     * &lt;p&gt;<a name="line.129"></a>
<span class="sourceLineNo">130</span>     * Note this implies the database initialization must initialize the database to its current, up-to-date state<a name="line.130"></a>
<span class="sourceLineNo">131</span>     * (with respect to the set of all available updates), not its original, pre-update state.<a name="line.131"></a>
<span class="sourceLineNo">132</span>     *<a name="line.132"></a>
<span class="sourceLineNo">133</span>     * &lt;p&gt;<a name="line.133"></a>
<span class="sourceLineNo">134</span>     * The database initialization step, and each of the update steps, is {@linkplain #applyInTransaction performed within<a name="line.134"></a>
<span class="sourceLineNo">135</span>     * its own transaction}.<a name="line.135"></a>
<span class="sourceLineNo">136</span>     *<a name="line.136"></a>
<span class="sourceLineNo">137</span>     * @param database the database to initialize (if necessary) and update<a name="line.137"></a>
<span class="sourceLineNo">138</span>     * @throws Exception if an update fails<a name="line.138"></a>
<span class="sourceLineNo">139</span>     * @throws UnrecognizedUpdateException if this instance is not configured to {@linkplain #setIgnoreUnrecognizedUpdates ignore<a name="line.139"></a>
<span class="sourceLineNo">140</span>     * unrecognized updates} and an unrecognized update has already been applied<a name="line.140"></a>
<span class="sourceLineNo">141</span>     * @throws IllegalArgumentException if two configured updates have the same name<a name="line.141"></a>
<span class="sourceLineNo">142</span>     * @throws IllegalArgumentException if any configured update has a required predecessor which is not also a configured update<a name="line.142"></a>
<span class="sourceLineNo">143</span>     *  (i.e., if the updates are not transitively closed under predecessors)<a name="line.143"></a>
<span class="sourceLineNo">144</span>     */<a name="line.144"></a>
<span class="sourceLineNo">145</span>    public synchronized void initializeAndUpdateDatabase(final D database) throws Exception {<a name="line.145"></a>
<span class="sourceLineNo">146</span><a name="line.146"></a>
<span class="sourceLineNo">147</span>        // Log<a name="line.147"></a>
<span class="sourceLineNo">148</span>        this.log.info("verifying database " + database);<a name="line.148"></a>
<span class="sourceLineNo">149</span><a name="line.149"></a>
<span class="sourceLineNo">150</span>        // First, initialize if necessary<a name="line.150"></a>
<span class="sourceLineNo">151</span>        this.applyInTransaction(database, new DatabaseAction&lt;T&gt;() {<a name="line.151"></a>
<span class="sourceLineNo">152</span>            @Override<a name="line.152"></a>
<span class="sourceLineNo">153</span>            public void apply(T transaction) throws Exception {<a name="line.153"></a>
<span class="sourceLineNo">154</span><a name="line.154"></a>
<span class="sourceLineNo">155</span>                // Already initialized?<a name="line.155"></a>
<span class="sourceLineNo">156</span>                if (!AbstractSchemaUpdater.this.databaseNeedsInitialization(transaction)) {<a name="line.156"></a>
<span class="sourceLineNo">157</span>                    AbstractSchemaUpdater.this.log.debug("detected already-initialized database " + database);<a name="line.157"></a>
<span class="sourceLineNo">158</span>                    return;<a name="line.158"></a>
<span class="sourceLineNo">159</span>                }<a name="line.159"></a>
<span class="sourceLineNo">160</span><a name="line.160"></a>
<span class="sourceLineNo">161</span>                // Initialize database<a name="line.161"></a>
<span class="sourceLineNo">162</span>                AbstractSchemaUpdater.this.log.info("uninitialized database detected; initializing " + database);<a name="line.162"></a>
<span class="sourceLineNo">163</span>                AbstractSchemaUpdater.this.initializeDatabase(transaction);<a name="line.163"></a>
<span class="sourceLineNo">164</span><a name="line.164"></a>
<span class="sourceLineNo">165</span>                // Record all schema updates as having already been applied<a name="line.165"></a>
<span class="sourceLineNo">166</span>                for (String updateName : AbstractSchemaUpdater.this.getAllUpdateNames())<a name="line.166"></a>
<span class="sourceLineNo">167</span>                    AbstractSchemaUpdater.this.recordUpdateApplied(transaction, updateName);<a name="line.167"></a>
<span class="sourceLineNo">168</span>            }<a name="line.168"></a>
<span class="sourceLineNo">169</span>        });<a name="line.169"></a>
<span class="sourceLineNo">170</span><a name="line.170"></a>
<span class="sourceLineNo">171</span>        // Next, apply any new updates<a name="line.171"></a>
<span class="sourceLineNo">172</span>        this.applySchemaUpdates(database);<a name="line.172"></a>
<span class="sourceLineNo">173</span><a name="line.173"></a>
<span class="sourceLineNo">174</span>        // Done<a name="line.174"></a>
<span class="sourceLineNo">175</span>        this.log.info("database verification completed for " + database);<a name="line.175"></a>
<span class="sourceLineNo">176</span>    }<a name="line.176"></a>
<span class="sourceLineNo">177</span><a name="line.177"></a>
<span class="sourceLineNo">178</span>    /**<a name="line.178"></a>
<span class="sourceLineNo">179</span>     * Determine if the given schema update name is valid. Valid names are non-empty and<a name="line.179"></a>
<span class="sourceLineNo">180</span>     * have no leading or trailing whitespace.<a name="line.180"></a>
<span class="sourceLineNo">181</span>     */<a name="line.181"></a>
<span class="sourceLineNo">182</span>    public static boolean isValidUpdateName(String updateName) {<a name="line.182"></a>
<span class="sourceLineNo">183</span>        return updateName.length() &gt; 0 &amp;&amp; updateName.trim().length() == updateName.length();<a name="line.183"></a>
<span class="sourceLineNo">184</span>    }<a name="line.184"></a>
<span class="sourceLineNo">185</span><a name="line.185"></a>
<span class="sourceLineNo">186</span>    /**<a name="line.186"></a>
<span class="sourceLineNo">187</span>     * Determine if the database needs initialization.<a name="line.187"></a>
<span class="sourceLineNo">188</span>     *<a name="line.188"></a>
<span class="sourceLineNo">189</span>     * &lt;p&gt;<a name="line.189"></a>
<span class="sourceLineNo">190</span>     * If so, {@link #initializeDatabase} will eventually be invoked.<a name="line.190"></a>
<span class="sourceLineNo">191</span>     *<a name="line.191"></a>
<span class="sourceLineNo">192</span>     * @param transaction open transaction<a name="line.192"></a>
<span class="sourceLineNo">193</span>     * @throws Exception if an error occurs while accessing the database<a name="line.193"></a>
<span class="sourceLineNo">194</span>     */<a name="line.194"></a>
<span class="sourceLineNo">195</span>    protected abstract boolean databaseNeedsInitialization(T transaction) throws Exception;<a name="line.195"></a>
<span class="sourceLineNo">196</span><a name="line.196"></a>
<span class="sourceLineNo">197</span>    /**<a name="line.197"></a>
<span class="sourceLineNo">198</span>     * Initialize an uninitialized database. This should create and initialize the database schema and content,<a name="line.198"></a>
<span class="sourceLineNo">199</span>     * including whatever portion of that is used to track schema updates.<a name="line.199"></a>
<span class="sourceLineNo">200</span>     *<a name="line.200"></a>
<span class="sourceLineNo">201</span>     * @param transaction open transaction<a name="line.201"></a>
<span class="sourceLineNo">202</span>     * @throws Exception if an error occurs while accessing the database<a name="line.202"></a>
<span class="sourceLineNo">203</span>     */<a name="line.203"></a>
<span class="sourceLineNo">204</span>    protected abstract void initializeDatabase(T transaction) throws Exception;<a name="line.204"></a>
<span class="sourceLineNo">205</span><a name="line.205"></a>
<span class="sourceLineNo">206</span>    /**<a name="line.206"></a>
<span class="sourceLineNo">207</span>     * Begin a transaction on the given database.<a name="line.207"></a>
<span class="sourceLineNo">208</span>     * The transaction will always eventually either be<a name="line.208"></a>
<span class="sourceLineNo">209</span>     * {@linkplain #commitTransaction committed} or {@linkplain #rollbackTransaction rolled back}.<a name="line.209"></a>
<span class="sourceLineNo">210</span>     *<a name="line.210"></a>
<span class="sourceLineNo">211</span>     * @param database database<a name="line.211"></a>
<span class="sourceLineNo">212</span>     * @return transaction handle<a name="line.212"></a>
<span class="sourceLineNo">213</span>     * @throws Exception if an error occurs while accessing the database<a name="line.213"></a>
<span class="sourceLineNo">214</span>     */<a name="line.214"></a>
<span class="sourceLineNo">215</span>    protected abstract T openTransaction(D database) throws Exception;<a name="line.215"></a>
<span class="sourceLineNo">216</span><a name="line.216"></a>
<span class="sourceLineNo">217</span>    /**<a name="line.217"></a>
<span class="sourceLineNo">218</span>     * Commit a previously opened transaction.<a name="line.218"></a>
<span class="sourceLineNo">219</span>     *<a name="line.219"></a>
<span class="sourceLineNo">220</span>     * @param transaction open transaction previously returned from {@link #openTransaction openTransaction()}<a name="line.220"></a>
<span class="sourceLineNo">221</span>     * @throws Exception if an error occurs while accessing the database<a name="line.221"></a>
<span class="sourceLineNo">222</span>     */<a name="line.222"></a>
<span class="sourceLineNo">223</span>    protected abstract void commitTransaction(T transaction) throws Exception;<a name="line.223"></a>
<span class="sourceLineNo">224</span><a name="line.224"></a>
<span class="sourceLineNo">225</span>    /**<a name="line.225"></a>
<span class="sourceLineNo">226</span>     * Roll back a previously opened transaction.<a name="line.226"></a>
<span class="sourceLineNo">227</span>     * This method will also be invoked if {@link #commitTransaction commitTransaction()} throws an exception.<a name="line.227"></a>
<span class="sourceLineNo">228</span>     *<a name="line.228"></a>
<span class="sourceLineNo">229</span>     * @param transaction open transaction previously returned from {@link #openTransaction openTransaction()}<a name="line.229"></a>
<span class="sourceLineNo">230</span>     * @throws Exception if an error occurs while accessing the database<a name="line.230"></a>
<span class="sourceLineNo">231</span>     */<a name="line.231"></a>
<span class="sourceLineNo">232</span>    protected abstract void rollbackTransaction(T transaction) throws Exception;<a name="line.232"></a>
<span class="sourceLineNo">233</span><a name="line.233"></a>
<span class="sourceLineNo">234</span>    /**<a name="line.234"></a>
<span class="sourceLineNo">235</span>     * Determine which updates have already been applied to the database.<a name="line.235"></a>
<span class="sourceLineNo">236</span>     *<a name="line.236"></a>
<span class="sourceLineNo">237</span>     * @param transaction open transaction<a name="line.237"></a>
<span class="sourceLineNo">238</span>     * @throws Exception if an error occurs while accessing the database<a name="line.238"></a>
<span class="sourceLineNo">239</span>     */<a name="line.239"></a>
<span class="sourceLineNo">240</span>    protected abstract Set&lt;String&gt; getAppliedUpdateNames(T transaction) throws Exception;<a name="line.240"></a>
<span class="sourceLineNo">241</span><a name="line.241"></a>
<span class="sourceLineNo">242</span>    /**<a name="line.242"></a>
<span class="sourceLineNo">243</span>     * Record an update as having been applied to the database.<a name="line.243"></a>
<span class="sourceLineNo">244</span>     *<a name="line.244"></a>
<span class="sourceLineNo">245</span>     * @param transaction open transaction<a name="line.245"></a>
<span class="sourceLineNo">246</span>     * @param name update name<a name="line.246"></a>
<span class="sourceLineNo">247</span>     * @throws IllegalStateException if the update has already been recorded in the database<a name="line.247"></a>
<span class="sourceLineNo">248</span>     * @throws Exception if an error occurs while accessing the database<a name="line.248"></a>
<span class="sourceLineNo">249</span>     */<a name="line.249"></a>
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<span class="sourceLineNo">251</span><a name="line.251"></a>
<span class="sourceLineNo">252</span>    /**<a name="line.252"></a>
<span class="sourceLineNo">253</span>     * Determine the preferred ordering of two updates that do not have any predecessor constraints<a name="line.253"></a>
<span class="sourceLineNo">254</span>     * (including implied indirect constraints) between them.<a name="line.254"></a>
<span class="sourceLineNo">255</span>     *<a name="line.255"></a>
<span class="sourceLineNo">256</span>     * &lt;p&gt;<a name="line.256"></a>
<span class="sourceLineNo">257</span>     * The {@link Comparator} returned by the implementation in {@link AbstractSchemaUpdater} simply sorts updates by name.<a name="line.257"></a>
<span class="sourceLineNo">258</span>     * Subclasses may override if necessary.<a name="line.258"></a>
<span class="sourceLineNo">259</span>     *<a name="line.259"></a>
<span class="sourceLineNo">260</span>     * @return a {@link Comparator} that sorts incomparable updates in the order they should be applied<a name="line.260"></a>
<span class="sourceLineNo">261</span>     */<a name="line.261"></a>
<span class="sourceLineNo">262</span>    protected Comparator&lt;SchemaUpdate&lt;T&gt;&gt; getOrderingTieBreaker() {<a name="line.262"></a>
<span class="sourceLineNo">263</span>        return new UpdateByNameComparator();<a name="line.263"></a>
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<span class="sourceLineNo">265</span><a name="line.265"></a>
<span class="sourceLineNo">266</span>    /**<a name="line.266"></a>
<span class="sourceLineNo">267</span>     * Generate the update name for one action within a multi-action update.<a name="line.267"></a>
<span class="sourceLineNo">268</span>     *<a name="line.268"></a>
<span class="sourceLineNo">269</span>     * &lt;p&gt;<a name="line.269"></a>
<span class="sourceLineNo">270</span>     * The implementation in {@link AbstractSchemaUpdater} just adds a suffix using {@code index + 1}, padded to<a name="line.270"></a>
<span class="sourceLineNo">271</span>     * 5 digits, producing names like {@code name-00001}, {@code name-00002}, etc.<a name="line.271"></a>
<span class="sourceLineNo">272</span>     *<a name="line.272"></a>
<span class="sourceLineNo">273</span>     * @param update the schema update<a name="line.273"></a>
<span class="sourceLineNo">274</span>     * @param index the index of the action (zero based)<a name="line.274"></a>
<span class="sourceLineNo">275</span>     * @see SchemaUpdate#isSingleAction<a name="line.275"></a>
<span class="sourceLineNo">276</span>     */<a name="line.276"></a>
<span class="sourceLineNo">277</span>    protected String generateMultiUpdateName(SchemaUpdate&lt;T&gt; update, int index) {<a name="line.277"></a>
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<span class="sourceLineNo">280</span><a name="line.280"></a>
<span class="sourceLineNo">281</span>    /**<a name="line.281"></a>
<span class="sourceLineNo">282</span>     * Get the names of all updates including multi-action updates.<a name="line.282"></a>
<span class="sourceLineNo">283</span>     */<a name="line.283"></a>
<span class="sourceLineNo">284</span>    protected List&lt;String&gt; getAllUpdateNames() throws Exception {<a name="line.284"></a>
<span class="sourceLineNo">285</span>        ArrayList&lt;SchemaUpdate&lt;T&gt;&gt; updateList = new ArrayList&lt;SchemaUpdate&lt;T&gt;&gt;(this.getUpdates());<a name="line.285"></a>
<span class="sourceLineNo">286</span>        ArrayList&lt;String&gt; updateNameList = new ArrayList&lt;String&gt;(updateList.size());<a name="line.286"></a>
<span class="sourceLineNo">287</span>        Collections.sort(updateList, new UpdateByNameComparator());<a name="line.287"></a>
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<span class="sourceLineNo">289</span>            updateNameList.addAll(this.getUpdateNames(update));<a name="line.289"></a>
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<span class="sourceLineNo">292</span><a name="line.292"></a>
<span class="sourceLineNo">293</span>    /**<a name="line.293"></a>
<span class="sourceLineNo">294</span>     * Execute a database action within an existing transaction.<a name="line.294"></a>
<span class="sourceLineNo">295</span>     *<a name="line.295"></a>
<span class="sourceLineNo">296</span>     * &lt;p&gt;<a name="line.296"></a>
<span class="sourceLineNo">297</span>     * All database operations in {@link AbstractSchemaUpdater} are performed via this method;<a name="line.297"></a>
<span class="sourceLineNo">298</span>     * subclasses are encouraged to follow this pattern.<a name="line.298"></a>
<span class="sourceLineNo">299</span>     *<a name="line.299"></a>
<span class="sourceLineNo">300</span>     * &lt;p&gt;<a name="line.300"></a>
<span class="sourceLineNo">301</span>     * The implementation in {@link AbstractSchemaUpdater} simply invokes {@link DatabaseAction#apply action.apply()};<a name="line.301"></a>
<span class="sourceLineNo">302</span>     * subclasses may override if desired.<a name="line.302"></a>
<span class="sourceLineNo">303</span>     *<a name="line.303"></a>
<span class="sourceLineNo">304</span>     * @throws Exception if an error occurs while accessing the database<a name="line.304"></a>
<span class="sourceLineNo">305</span>     */<a name="line.305"></a>
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<span class="sourceLineNo">309</span><a name="line.309"></a>
<span class="sourceLineNo">310</span>    /**<a name="line.310"></a>
<span class="sourceLineNo">311</span>     * Execute a database action. A new transaction will be created, used, and closed.<a name="line.311"></a>
<span class="sourceLineNo">312</span>     * Delegates to {@link #apply apply()} for the actual execution of the action.<a name="line.312"></a>
<span class="sourceLineNo">313</span>     *<a name="line.313"></a>
<span class="sourceLineNo">314</span>     * &lt;p&gt;<a name="line.314"></a>
<span class="sourceLineNo">315</span>     * If the action or {@link #commitTransaction commitTransaction()} fails, the transaction<a name="line.315"></a>
<span class="sourceLineNo">316</span>     * is {@linkplain #rollbackTransaction rolled back}.<a name="line.316"></a>
<span class="sourceLineNo">317</span>     *<a name="line.317"></a>
<span class="sourceLineNo">318</span>     * @throws Exception if an error occurs while accessing the database<a name="line.318"></a>
<span class="sourceLineNo">319</span>     */<a name="line.319"></a>
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<span class="sourceLineNo">321</span>        T transaction = this.openTransaction(database);<a name="line.321"></a>
<span class="sourceLineNo">322</span>        boolean success = false;<a name="line.322"></a>
<span class="sourceLineNo">323</span>        try {<a name="line.323"></a>
<span class="sourceLineNo">324</span>            this.apply(transaction, action);<a name="line.324"></a>
<span class="sourceLineNo">325</span>            this.commitTransaction(transaction);<a name="line.325"></a>
<span class="sourceLineNo">326</span>            success = true;<a name="line.326"></a>
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<span class="sourceLineNo">329</span>                this.rollbackTransaction(transaction);<a name="line.329"></a>
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<span class="sourceLineNo">332</span><a name="line.332"></a>
<span class="sourceLineNo">333</span>    /**<a name="line.333"></a>
<span class="sourceLineNo">334</span>     * Apply schema updates to an initialized database.<a name="line.334"></a>
<span class="sourceLineNo">335</span>     */<a name="line.335"></a>
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<span class="sourceLineNo">337</span><a name="line.337"></a>
<span class="sourceLineNo">338</span>        // Sanity check<a name="line.338"></a>
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<span class="sourceLineNo">340</span>            throw new IllegalArgumentException("no updates configured");<a name="line.340"></a>
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<span class="sourceLineNo">342</span><a name="line.342"></a>
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<span class="sourceLineNo">344</span>        TreeMap&lt;String, SchemaUpdate&lt;T&gt;&gt; updateMap = new TreeMap&lt;String, SchemaUpdate&lt;T&gt;&gt;();<a name="line.344"></a>
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<span class="sourceLineNo">346</span>            for (String updateName : this.getUpdateNames(update)) {<a name="line.346"></a>
<span class="sourceLineNo">347</span>                if (!isValidUpdateName(updateName))<a name="line.347"></a>
<span class="sourceLineNo">348</span>                    throw new IllegalArgumentException("illegal schema update name `" + updateName + "'");<a name="line.348"></a>
<span class="sourceLineNo">349</span>                if (updateMap.put(updateName, update) != null)<a name="line.349"></a>
<span class="sourceLineNo">350</span>                    throw new IllegalArgumentException("duplicate schema update name `" + updateName + "'");<a name="line.350"></a>
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<span class="sourceLineNo">353</span>        this.log.debug("these are all known schema updates: " + updateMap.keySet());<a name="line.353"></a>
<span class="sourceLineNo">354</span><a name="line.354"></a>
<span class="sourceLineNo">355</span>        // Verify updates are transitively closed under predecessor constraints<a name="line.355"></a>
<span class="sourceLineNo">356</span>        for (SchemaUpdate&lt;T&gt; update : allUpdates) {<a name="line.356"></a>
<span class="sourceLineNo">357</span>            for (SchemaUpdate&lt;T&gt; predecessor : update.getRequiredPredecessors()) {<a name="line.357"></a>
<span class="sourceLineNo">358</span>                if (!allUpdates.contains(predecessor)) {<a name="line.358"></a>
<span class="sourceLineNo">359</span>                    throw new IllegalArgumentException("schema update `" + update.getName()<a name="line.359"></a>
<span class="sourceLineNo">360</span>                      + "' has a required predecessor named `" + predecessor.getName() + "' that is not a configured update");<a name="line.360"></a>
<span class="sourceLineNo">361</span>                }<a name="line.361"></a>
<span class="sourceLineNo">362</span>            }<a name="line.362"></a>
<span class="sourceLineNo">363</span>        }<a name="line.363"></a>
<span class="sourceLineNo">364</span><a name="line.364"></a>
<span class="sourceLineNo">365</span>        // Sort updates in the order we should to apply them<a name="line.365"></a>
<span class="sourceLineNo">366</span>        List&lt;SchemaUpdate&lt;T&gt;&gt; updateList = new TopologicalSorter&lt;SchemaUpdate&lt;T&gt;&gt;(allUpdates,<a name="line.366"></a>
<span class="sourceLineNo">367</span>          new SchemaUpdateEdgeLister&lt;T&gt;(), this.getOrderingTieBreaker()).sortEdgesReversed();<a name="line.367"></a>
<span class="sourceLineNo">368</span><a name="line.368"></a>
<span class="sourceLineNo">369</span>        // Determine which updates have already been applied<a name="line.369"></a>
<span class="sourceLineNo">370</span>        final HashSet&lt;String&gt; appliedUpdateNames = new HashSet&lt;String&gt;();<a name="line.370"></a>
<span class="sourceLineNo">371</span>        this.applyInTransaction(database, new DatabaseAction&lt;T&gt;() {<a name="line.371"></a>
<span class="sourceLineNo">372</span>            @Override<a name="line.372"></a>
<span class="sourceLineNo">373</span>            public void apply(T transaction) throws Exception {<a name="line.373"></a>
<span class="sourceLineNo">374</span>                appliedUpdateNames.addAll(AbstractSchemaUpdater.this.getAppliedUpdateNames(transaction));<a name="line.374"></a>
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<span class="sourceLineNo">376</span>        });<a name="line.376"></a>
<span class="sourceLineNo">377</span>        this.log.debug("these are the already-applied schema updates: " + appliedUpdateNames);<a name="line.377"></a>
<span class="sourceLineNo">378</span><a name="line.378"></a>
<span class="sourceLineNo">379</span>        // Check whether any unknown updates have been applied<a name="line.379"></a>
<span class="sourceLineNo">380</span>        TreeSet&lt;String&gt; unknownUpdateNames = new TreeSet&lt;String&gt;(appliedUpdateNames);<a name="line.380"></a>
<span class="sourceLineNo">381</span>        unknownUpdateNames.removeAll(updateMap.keySet());<a name="line.381"></a>
<span class="sourceLineNo">382</span>        if (!unknownUpdateNames.isEmpty()) {<a name="line.382"></a>
<span class="sourceLineNo">383</span>            if (!this.isIgnoreUnrecognizedUpdates()) {<a name="line.383"></a>
<span class="sourceLineNo">384</span>                throw new UnrecognizedUpdateException(unknownUpdateNames.size()<a name="line.384"></a>
<span class="sourceLineNo">385</span>                  + " unrecognized update(s) have already been applied: " + unknownUpdateNames);<a name="line.385"></a>
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<span class="sourceLineNo">387</span>            this.log.info("ignoring " + unknownUpdateNames.size()<a name="line.387"></a>
<span class="sourceLineNo">388</span>              + " unrecognized update(s) already applied: " + unknownUpdateNames);<a name="line.388"></a>
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<span class="sourceLineNo">390</span><a name="line.390"></a>
<span class="sourceLineNo">391</span>        // Remove the already-applied updates<a name="line.391"></a>
<span class="sourceLineNo">392</span>        updateMap.keySet().removeAll(appliedUpdateNames);<a name="line.392"></a>
<span class="sourceLineNo">393</span>        HashSet&lt;SchemaUpdate&lt;T&gt;&gt; remainingUpdates = new HashSet&lt;SchemaUpdate&lt;T&gt;&gt;(updateMap.values());<a name="line.393"></a>
<span class="sourceLineNo">394</span>        for (Iterator&lt;SchemaUpdate&lt;T&gt;&gt; i = updateList.iterator(); i.hasNext(); ) {<a name="line.394"></a>
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<span class="sourceLineNo">396</span>                i.remove();<a name="line.396"></a>
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<span class="sourceLineNo">398</span><a name="line.398"></a>
<span class="sourceLineNo">399</span>        // Now are any updates needed?<a name="line.399"></a>
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<span class="sourceLineNo">401</span>            this.log.info("no schema updates are required");<a name="line.401"></a>
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<span class="sourceLineNo">404</span><a name="line.404"></a>
<span class="sourceLineNo">405</span>        // Log which updates we're going to apply<a name="line.405"></a>
<span class="sourceLineNo">406</span>        final LinkedHashSet&lt;String&gt; remainingUpdateNames = new LinkedHashSet&lt;String&gt;(updateMap.size());<a name="line.406"></a>
<span class="sourceLineNo">407</span>        for (SchemaUpdate&lt;T&gt; update : updateList) {<a name="line.407"></a>
<span class="sourceLineNo">408</span>            ArrayList&lt;String&gt; updateNames = this.getUpdateNames(update);<a name="line.408"></a>
<span class="sourceLineNo">409</span>            updateNames.removeAll(appliedUpdateNames);<a name="line.409"></a>
<span class="sourceLineNo">410</span>            remainingUpdateNames.addAll(updateNames);<a name="line.410"></a>
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<span class="sourceLineNo">412</span>        this.log.info("applying " + remainingUpdateNames.size() + " schema update(s): " + remainingUpdateNames);<a name="line.412"></a>
<span class="sourceLineNo">413</span><a name="line.413"></a>
<span class="sourceLineNo">414</span>        // Apply and record each unapplied update<a name="line.414"></a>
<span class="sourceLineNo">415</span>        for (SchemaUpdate&lt;T&gt; nextUpdate : updateList) {<a name="line.415"></a>
<span class="sourceLineNo">416</span>            final RecordingUpdateHandler updateHandler = new RecordingUpdateHandler(nextUpdate, remainingUpdateNames);<a name="line.416"></a>
<span class="sourceLineNo">417</span>            this.applyInTransaction(database, new DatabaseAction&lt;T&gt;() {<a name="line.417"></a>
<span class="sourceLineNo">418</span>                @Override<a name="line.418"></a>
<span class="sourceLineNo">419</span>                public void apply(T transaction) throws Exception {<a name="line.419"></a>
<span class="sourceLineNo">420</span>                    updateHandler.process(transaction);<a name="line.420"></a>
<span class="sourceLineNo">421</span>                }<a name="line.421"></a>
<span class="sourceLineNo">422</span>            });<a name="line.422"></a>
<span class="sourceLineNo">423</span>        }<a name="line.423"></a>
<span class="sourceLineNo">424</span>    }<a name="line.424"></a>
<span class="sourceLineNo">425</span><a name="line.425"></a>
<span class="sourceLineNo">426</span>    // Get all update names, expanding multi-updates as necessary<a name="line.426"></a>
<span class="sourceLineNo">427</span>    private ArrayList&lt;String&gt; getUpdateNames(SchemaUpdate&lt;T&gt; update) throws Exception {<a name="line.427"></a>
<span class="sourceLineNo">428</span>        final ArrayList&lt;String&gt; names = new ArrayList&lt;String&gt;();<a name="line.428"></a>
<span class="sourceLineNo">429</span>        UpdateHandler updateHandler = new UpdateHandler(update) {<a name="line.429"></a>
<span class="sourceLineNo">430</span>            @Override<a name="line.430"></a>
<span class="sourceLineNo">431</span>            protected void handleSingleUpdate(T transaction, DatabaseAction&lt;T&gt; action) {<a name="line.431"></a>
<span class="sourceLineNo">432</span>                names.add(this.update.getName());<a name="line.432"></a>
<span class="sourceLineNo">433</span>            }<a name="line.433"></a>
<span class="sourceLineNo">434</span>            @Override<a name="line.434"></a>
<span class="sourceLineNo">435</span>            protected void handleMultiUpdate(T transaction, DatabaseAction&lt;T&gt; action, int index) {<a name="line.435"></a>
<span class="sourceLineNo">436</span>                names.add(AbstractSchemaUpdater.this.generateMultiUpdateName(this.update, index));<a name="line.436"></a>
<span class="sourceLineNo">437</span>            }<a name="line.437"></a>
<span class="sourceLineNo">438</span>        };<a name="line.438"></a>
<span class="sourceLineNo">439</span>        updateHandler.process(null);<a name="line.439"></a>
<span class="sourceLineNo">440</span>        return names;<a name="line.440"></a>
<span class="sourceLineNo">441</span>    }<a name="line.441"></a>
<span class="sourceLineNo">442</span><a name="line.442"></a>
<span class="sourceLineNo">443</span>    // Apply and record an update, all within a single transaction<a name="line.443"></a>
<span class="sourceLineNo">444</span>    private void applyAndRecordUpdate(T transaction, String name, final DatabaseAction&lt;T&gt; action) throws Exception {<a name="line.444"></a>
<span class="sourceLineNo">445</span>        if (action != null) {<a name="line.445"></a>
<span class="sourceLineNo">446</span>            this.log.info("applying schema update `" + name + "'");<a name="line.446"></a>
<span class="sourceLineNo">447</span>            this.apply(transaction, action);<a name="line.447"></a>
<span class="sourceLineNo">448</span>        } else<a name="line.448"></a>
<span class="sourceLineNo">449</span>            this.log.info("recording empty schema update `" + name + "'");<a name="line.449"></a>
<span class="sourceLineNo">450</span>        this.recordUpdateApplied(transaction, name);<a name="line.450"></a>
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<span class="sourceLineNo">452</span><a name="line.452"></a>
<span class="sourceLineNo">453</span>    private class RecordingUpdateHandler extends UpdateHandler {<a name="line.453"></a>
<span class="sourceLineNo">454</span><a name="line.454"></a>
<span class="sourceLineNo">455</span>        private final Set&lt;String&gt; remainingUpdateNames;<a name="line.455"></a>
<span class="sourceLineNo">456</span><a name="line.456"></a>
<span class="sourceLineNo">457</span>        public RecordingUpdateHandler(SchemaUpdate&lt;T&gt; update, Set&lt;String&gt; remainingUpdateNames) {<a name="line.457"></a>
<span class="sourceLineNo">458</span>            super(update);<a name="line.458"></a>
<span class="sourceLineNo">459</span>            this.remainingUpdateNames = remainingUpdateNames;<a name="line.459"></a>
<span class="sourceLineNo">460</span>        }<a name="line.460"></a>
<span class="sourceLineNo">461</span><a name="line.461"></a>
<span class="sourceLineNo">462</span>        @Override<a name="line.462"></a>
<span class="sourceLineNo">463</span>        protected void handleEmptyUpdate(T transaction) throws Exception {<a name="line.463"></a>
<span class="sourceLineNo">464</span>            assert this.remainingUpdateNames.contains(this.update.getName());<a name="line.464"></a>
<span class="sourceLineNo">465</span>            AbstractSchemaUpdater.this.applyAndRecordUpdate(transaction, this.update.getName(), null);<a name="line.465"></a>
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<span class="sourceLineNo">467</span><a name="line.467"></a>
<span class="sourceLineNo">468</span>        @Override<a name="line.468"></a>
<span class="sourceLineNo">469</span>        protected void handleSingleUpdate(T transaction, DatabaseAction&lt;T&gt; action) throws Exception {<a name="line.469"></a>
<span class="sourceLineNo">470</span>            assert this.remainingUpdateNames.contains(this.update.getName());<a name="line.470"></a>
<span class="sourceLineNo">471</span>            AbstractSchemaUpdater.this.applyAndRecordUpdate(transaction, this.update.getName(), action);<a name="line.471"></a>
<span class="sourceLineNo">472</span>        }<a name="line.472"></a>
<span class="sourceLineNo">473</span><a name="line.473"></a>
<span class="sourceLineNo">474</span>        @Override<a name="line.474"></a>
<span class="sourceLineNo">475</span>        protected void handleSingleMultiUpdate(T transaction, final List&lt;? extends DatabaseAction&lt;T&gt;&gt; actions)<a name="line.475"></a>
<span class="sourceLineNo">476</span>          throws Exception {<a name="line.476"></a>
<span class="sourceLineNo">477</span>            assert this.remainingUpdateNames.contains(this.update.getName());<a name="line.477"></a>
<span class="sourceLineNo">478</span>            AbstractSchemaUpdater.this.applyAndRecordUpdate(transaction, this.update.getName(), new DatabaseAction&lt;T&gt;() {<a name="line.478"></a>
<span class="sourceLineNo">479</span>                @Override<a name="line.479"></a>
<span class="sourceLineNo">480</span>                public void apply(T transaction) throws Exception {<a name="line.480"></a>
<span class="sourceLineNo">481</span>                    for (DatabaseAction&lt;T&gt; action : actions)<a name="line.481"></a>
<span class="sourceLineNo">482</span>                        AbstractSchemaUpdater.this.apply(transaction, action);<a name="line.482"></a>
<span class="sourceLineNo">483</span>                }<a name="line.483"></a>
<span class="sourceLineNo">484</span>            });<a name="line.484"></a>
<span class="sourceLineNo">485</span>        }<a name="line.485"></a>
<span class="sourceLineNo">486</span><a name="line.486"></a>
<span class="sourceLineNo">487</span>        @Override<a name="line.487"></a>
<span class="sourceLineNo">488</span>        protected void handleMultiUpdate(T transaction, DatabaseAction&lt;T&gt; action, int index) throws Exception {<a name="line.488"></a>
<span class="sourceLineNo">489</span>            String updateName = AbstractSchemaUpdater.this.generateMultiUpdateName(this.update, index);<a name="line.489"></a>
<span class="sourceLineNo">490</span>            if (!this.remainingUpdateNames.contains(updateName))                 // a partially completed multi-update<a name="line.490"></a>
<span class="sourceLineNo">491</span>                return;<a name="line.491"></a>
<span class="sourceLineNo">492</span>            AbstractSchemaUpdater.this.applyAndRecordUpdate(transaction, updateName, action);<a name="line.492"></a>
<span class="sourceLineNo">493</span>        }<a name="line.493"></a>
<span class="sourceLineNo">494</span>    }<a name="line.494"></a>
<span class="sourceLineNo">495</span><a name="line.495"></a>
<span class="sourceLineNo">496</span>    // Adapter class for handling updates of various types<a name="line.496"></a>
<span class="sourceLineNo">497</span>    private class UpdateHandler {<a name="line.497"></a>
<span class="sourceLineNo">498</span><a name="line.498"></a>
<span class="sourceLineNo">499</span>        protected final SchemaUpdate&lt;T&gt; update;<a name="line.499"></a>
<span class="sourceLineNo">500</span><a name="line.500"></a>
<span class="sourceLineNo">501</span>        private final List&lt;? extends DatabaseAction&lt;T&gt;&gt; actions;<a name="line.501"></a>
<span class="sourceLineNo">502</span><a name="line.502"></a>
<span class="sourceLineNo">503</span>        public UpdateHandler(SchemaUpdate&lt;T&gt; update) {<a name="line.503"></a>
<span class="sourceLineNo">504</span>            this.update = update;<a name="line.504"></a>
<span class="sourceLineNo">505</span>            this.actions = update.getDatabaseActions();<a name="line.505"></a>
<span class="sourceLineNo">506</span>        }<a name="line.506"></a>
<span class="sourceLineNo">507</span><a name="line.507"></a>
<span class="sourceLineNo">508</span>        public final void process(T transaction) throws Exception {<a name="line.508"></a>
<span class="sourceLineNo">509</span>            switch (this.actions.size()) {<a name="line.509"></a>
<span class="sourceLineNo">510</span>            case 0:<a name="line.510"></a>
<span class="sourceLineNo">511</span>                this.handleEmptyUpdate(transaction);<a name="line.511"></a>
<span class="sourceLineNo">512</span>                break;<a name="line.512"></a>
<span class="sourceLineNo">513</span>            case 1:<a name="line.513"></a>
<span class="sourceLineNo">514</span>                this.handleSingleUpdate(transaction, this.actions.get(0));<a name="line.514"></a>
<span class="sourceLineNo">515</span>                break;<a name="line.515"></a>
<span class="sourceLineNo">516</span>            default:<a name="line.516"></a>
<span class="sourceLineNo">517</span>                if (update.isSingleAction()) {<a name="line.517"></a>
<span class="sourceLineNo">518</span>                    this.handleSingleMultiUpdate(transaction, actions);<a name="line.518"></a>
<span class="sourceLineNo">519</span>                    break;<a name="line.519"></a>
<span class="sourceLineNo">520</span>                } else {<a name="line.520"></a>
<span class="sourceLineNo">521</span>                    int index = 0;<a name="line.521"></a>
<span class="sourceLineNo">522</span>                    for (DatabaseAction&lt;T&gt; action : this.actions)<a name="line.522"></a>
<span class="sourceLineNo">523</span>                        this.handleMultiUpdate(transaction, action, index++);<a name="line.523"></a>
<span class="sourceLineNo">524</span>                }<a name="line.524"></a>
<span class="sourceLineNo">525</span>                break;<a name="line.525"></a>
<span class="sourceLineNo">526</span>            }<a name="line.526"></a>
<span class="sourceLineNo">527</span>        }<a name="line.527"></a>
<span class="sourceLineNo">528</span><a name="line.528"></a>
<span class="sourceLineNo">529</span>        protected void handleEmptyUpdate(T transaction) throws Exception {<a name="line.529"></a>
<span class="sourceLineNo">530</span>            this.handleSingleUpdate(transaction, null);<a name="line.530"></a>
<span class="sourceLineNo">531</span>        }<a name="line.531"></a>
<span class="sourceLineNo">532</span><a name="line.532"></a>
<span class="sourceLineNo">533</span>        protected void handleSingleUpdate(T transaction, DatabaseAction&lt;T&gt; action) throws Exception {<a name="line.533"></a>
<span class="sourceLineNo">534</span>        }<a name="line.534"></a>
<span class="sourceLineNo">535</span><a name="line.535"></a>
<span class="sourceLineNo">536</span>        protected void handleSingleMultiUpdate(T transaction, List&lt;? extends DatabaseAction&lt;T&gt;&gt; actions) throws Exception {<a name="line.536"></a>
<span class="sourceLineNo">537</span>            this.handleSingleUpdate(transaction, null);<a name="line.537"></a>
<span class="sourceLineNo">538</span>        }<a name="line.538"></a>
<span class="sourceLineNo">539</span><a name="line.539"></a>
<span class="sourceLineNo">540</span>        protected void handleMultiUpdate(T transaction, DatabaseAction&lt;T&gt; action, int index) throws Exception {<a name="line.540"></a>
<span class="sourceLineNo">541</span>        }<a name="line.541"></a>
<span class="sourceLineNo">542</span>    }<a name="line.542"></a>
<span class="sourceLineNo">543</span><a name="line.543"></a>
<span class="sourceLineNo">544</span>    // Sorts updates by name<a name="line.544"></a>
<span class="sourceLineNo">545</span>    private class UpdateByNameComparator implements Comparator&lt;SchemaUpdate&lt;T&gt;&gt; {<a name="line.545"></a>
<span class="sourceLineNo">546</span><a name="line.546"></a>
<span class="sourceLineNo">547</span>        @Override<a name="line.547"></a>
<span class="sourceLineNo">548</span>        public int compare(SchemaUpdate&lt;T&gt; update1, SchemaUpdate&lt;T&gt; update2) {<a name="line.548"></a>
<span class="sourceLineNo">549</span>            return update1.getName().compareTo(update2.getName());<a name="line.549"></a>
<span class="sourceLineNo">550</span>        }<a name="line.550"></a>
<span class="sourceLineNo">551</span>    }<a name="line.551"></a>
<span class="sourceLineNo">552</span>}<a name="line.552"></a>
<span class="sourceLineNo">553</span><a name="line.553"></a>




























































</pre>
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